The proposed research will study the structure and function of the gap junction as the site of intercellular communication. The junction structure will be studied using techniques of x-ray diffraction, electron microscopy, and biochemistry. Gap junctions from heart, liver and lens tissue will be compared. Comparison will be made by peptide mapping of proteolysis fragments of principal polypeptides electrophoretically isolated from different gap junction preparations. The function and biogenesis of gap junctions will be studied by raising monoclonal antibodies to the lens gap junction principal peptide. The antibodies will be used to study the cell and molecular biology of gap junction biosynthesis and assembly, looking for primary transcripts of mRNA from lens homogenates, and extrajunctional antigens with fluorescent antibodies. Freeze substitution autoradiography will be used to study metabolic cooperation at the organ level.